The North Atlantic Treaty Organization (NATO); French: Organisation du Traité de l'Atlantique Nord (OTAN); (also called the North Atlantic Alliance, the Atlantic Alliance, or the Western Alliance) is a military alliance established by the signing of the North Atlantic Treaty on 4 April 1949. The NATO headquarters are in Brussels, Belgium,[3] the organization constitutes a system of collective defense whereby its member states agree to mutual defense in response to an attack by any external party.

The flag of the North Atlantic Treaty Organization has a navy blue (Pantone 280) field charged with a white compass rose emblem from which radiate four white lines. It was approved 14 October 1953.